L10 - Nervous System 2

Flashcards about the global organization of the nervous system, focusing on cellular and molecular mechanisms involved in nerve transduction.

Neuron

The basic structural unit of the nervous system with approximately 86 billion in the human brain.

Glial Cells

Non-neuronal cells in the brain, numbering about 85 billion, that support neuronal function.

Cell Body

The part of the neuron containing the nucleus, also known as the cell soma.

Dendrites

Fine processes emanating from the cell body that receive information from other neurons.

Axon

A single process emanating from the cell body that transmits information to other neurons.

Action Potentials

Electrical currents that pass along the axon, coding information in the nervous system.

Intracellular Fluid

Fluid found within cells, comprising two-thirds of the total fluid in the body.

Extracellular Fluid

Fluid outside of cells and cell membranes, comprising one-third of the total fluid in the body.

Phospholipid Bilayer

The structure of the cell membrane, composed of phosphate heads and lipid tails, preventing water and water-soluble molecules from passing through.

Protein Transporters

Proteins in the cell membrane that allow the passage of non-lipid soluble molecules across the membrane.

Leak Channels

A type of protein that allows the passage of molecules across the cell membrane along the concentration gradient.

Gated Channels

A pore or channel through the cell membrane that opens and closes to allow the passage of molecules under specific circumstances.

Transporter Proteins

Transmembrane proteins that actively transport specific molecules across the cell membrane, requiring energy in the form of ATP.

Sodium Potassium ATPase

A pump that actively transports sodium ions from inside the cell to outside and potassium ions from outside to inside, maintaining their concentration gradients.

Resting Membrane Potential

The electrical potential across the cell membrane, typically around -65 to -70 millivolts in neurons.

Voltage Gated Ion Channels

Gated channels that open at a particular membrane potential, allowing specific ions to pass through.

Depolarization

The process of the resting membrane potential increasing from a negative value towards a positive value, initiated by the opening of voltage-gated sodium channels.

Repolarization

The phase when voltage-gated sodium channels close and voltage-gated potassium channels open, allowing potassium to exit the cell and decreasing the membrane potential.

Hyperpolarization

The phase where the membrane potential becomes more negative than the resting potential due to the dramatic efflux of potassium.

Myelination

A process where the speed of transmission of action potentials along axons is increased due to myelination.

Oligodendrocytes

Cells in the central nervous system responsible for myelinating the axons of neurons.

Schwann Cells

Cells in the peripheral nervous system responsible for myelinating the axons of neurons.

Nodes of Ranvier

Gaps between myelinated sections of the axon where there are high concentrations of voltage-gated channels.

Saltatory Conduction

The process by which action potentials jump along the axon from one node of Ranvier to the next, speeding up transmission.

Neurotransmitters

Chemicals found within neurons that transmit information across the synapse to neighboring neurons.

Synaptic Cleft

The gap between the presynaptic and postsynaptic membranes where neurotransmitters diffuse to transmit information.

Presynaptic Membrane

The region of the axon terminal that releases neurotransmitters.

Postsynaptic Membrane

The membrane of the dendrite that receives neurotransmitters.

Glutamate

A major excitatory neurotransmitter in the brain. Binds to receptor that opens Na⁺ channels. Na⁺ rushes in, causing membrane potential to increase a little bit (eg. -65 → -63). Causes excitatory post synaptic potentials (EPSPs).

GABA

A major inhibitory neurotransmitter in the brain. Binds to receptors that open Cl⁻ (chloride) or K⁺ (potassium) channels. Cl⁻ flows in (or K⁺ flows out), making the membrane potential more negative (e.g. –65 → –70). Causes inhibitory post synaptic potentials (IPSPs).

Acetylcholine

A major neurotransmitter in the brain and muscles. Binds to receptors that open Na⁺ channels (excitatory) or K⁺ channels (inhibitory), depending on receptor type. In the neuromuscular junction, causes Na⁺ to rush in, leading to muscle contraction. In the brain, involved in learning, memory, and attention.

Excitatory Postsynaptic Potential (EPSP)

A slight increase in the membrane potential of the postsynaptic neuron due to the influx of sodium, making an action potential more likely.

Inhibitory Postsynaptic Potential (IPSP)

A decrease in the membrane potential of the postsynaptic neuron due to the influx of chloride, making an action potential less likely.

Temporal Summation

The process where multiple action potentials in quick succession generate enough EPSPs to trigger an action potential in the postsynaptic neuron.

Spatial Summation

The process where multiple synaptic inputs onto different dendrites of a neuron collectively generate enough EPSPs to trigger an action potential.